It’s rare that the National Association for the Advancement of Colored People and the Congressional Black Caucus fall on opposite sides of a political issue, but the Internal Revenue Service’s proposed regulation of 501(c)(4) groups has put them at loggerheads.

While the NAACP last month issued a harsh critique of the controversial regulations, warning that they would cause many of the group’s regional branches to lose their tax-exempt status, every member of the CBC that case a vote on a House bill that would have delayed the implementation of the regulations for a year opposed the measure.

“As drafted, the proposed regulations would cause the ‘primary’ activity — by any measure — of these NAACP unites to be counted as ‘candidate-related political activity,’ with the result that most branches and conferences would lose their tax-exempt status,” the chairwoman of the NAACP’s board of directors, Roslyn M. Brock, and the group’s interim president and chief executive offer, wrote in a public comment to the IRS.

Other liberal groups including the American Civil Liberties Union and the Service Employees International Union have also spoken out against the regulations, which would classify much of the day-to-day activity of social-welfare groups — voter education, non-partisan voter registration, and get-out-the-vote activities — and limit the amount of those activities permitted under the law.

The curtailment of activities like voter education and registration is a matter of particular sensitivity for the NAACP, which told IRS that its regulations would prohibit much of the work the group did, in its early years, to battle race discrimination in the administration of the country’s voting laws. The IRS’s rule making, they said, ”should not be permitted to undermine the progress we have made over the past century to expand the franchise.”

In the wake of the Supreme Court’s 2010 ruling in Citizens United vs. Federal Election Commission, several Democratic lawmakers called on the IRS to reexamine the guidelines it uses to approve or deny tax exemption to social welfare groups, which have been on the books since 1959; New York senator Chuck Schumer in January urged Democrats to “redouble” their efforts to push for these administrative changes. While the NAACP said it agreed the IRS should not permit “powerful wealthy interests” to hide their campaign expenditures, it argued that the proposed rules would “make matters worse, not better, by further muddying the waters in this area of the law.”

But 40 House members of the Congressional Black Caucus, it seems, see things differently. That’s every member of the CBC who voted against a House bill introduced by Ways and Means Committee chairman Dave Camp that would have delayed the proposed regulations for a year. The bill passed the House late last month by a 243-176 margin; 14 Democrats joined the GOP in support for the measure. (Two members of the CBC, Minnesota’s Keith Ellison and New York’s Charlie Rangel, did not vote on the bill.)

It’s an odd split, and perhaps the Democrats whipped their members effectively or the NAACP didn’t circulate its comment on the Hill. A spokeswoman for the CBC did not respond to a request for comment on whether the CBC or its chairwoman, Marcia Fudge (D., Ohio) have taken an official position on the matter. The NAACP’s legal office did not return a call seeking comment. Both requests were made late this afternoon, and I will post updates if I receive them.